US5672998A - Class D amplifier and method - Google Patents
Class D amplifier and method Download PDFInfo
- Publication number
- US5672998A US5672998A US08/512,763 US51276395A US5672998A US 5672998 A US5672998 A US 5672998A US 51276395 A US51276395 A US 51276395A US 5672998 A US5672998 A US 5672998A
- Authority
- US
- United States
- Prior art keywords
- pulse width
- audio
- width modulated
- amplifier
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/217—Class D power amplifiers; Switching amplifiers
- H03F3/2171—Class D power amplifiers; Switching amplifiers with field-effect devices
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/217—Class D power amplifiers; Switching amplifiers
- H03F3/2173—Class D power amplifiers; Switching amplifiers of the bridge type
Definitions
- the present invention relates to amplifiers for audio systems, and more particularly to an improved feedback loop in a Class D amplifier that has less distortion.
- Class D amplifiers are known and only their feedback portion is of interest herein.
- a Class D amplifier may include conventional stages utilizing integrated circuit (IC) technology in which the complex driver function for the output bridge may be provided by a single IC, such as the Harris® HIP4080 family of ICs.
- IC integrated circuit
- a feedback loop for the amplifier typically includes a differential-to-single-ended converter for providing a pulsed sample of the output signal which is then integrated with the audio input signal, and then pulse width modulated to provide an input signal to the amplifier.
- the feedback loop is generally defined by the circuits connecting the converter, the integrator, and pulse width modulator. Because the feedback loop includes both integration and pulse width modulation stages, it includes the problems associated therewith.
- integration and “integrator” refers to the integration customarily found in the feedback loop of an audio feedback amplifier and not to the integration needed for phase or frequency compensation typically provided by inverters.
- the output circuit 10 includes a conventional amplifier 11 and two one-half bridge driver circuits for a speaker.
- the customary output filters associated with the speaker have been omitted from the figure.
- the feedback path of the audio output signal from speaker in the output circuit 10 at the terminals 12 and 14 thereof includes a conventional differential-to-single-ended-converter 16 which provides a pulsed output signal.
- This pulsed signal is integrated in a conventional integrator 18 where it is compared with the audio input signal from the input terminal 20.
- the output from the integrator 18 is applied to a comparator or pulse width modulator 22 to which a modulating triangular waveform from the generator 24 is also applied.
- the modulator 22 thus provides complementary pulse width modulated signals A and B to the output circuit 10.
- the integration process carried out in the feedback loop is bandwidth limiting and the performance of Class D amplifiers may be improved by avoiding this problem.
- the problem arises because the pulsed output from the differential-to-single-ended-converter must be removed from the signal in the feedback loop. This means that there is minimal correction of high frequencies by the feedback loop, thereby increasing distortion of the signal. Moreover, undesired residual signals from the pulse output may be reapplied in the pulse width modulator 22.
- the amplifier and associated driving circuits may be considered a wideband power amplifier, thereby obviating the need for integration in the feedback loop altogether.
- the signals fed back to the amplifier may be pulsed signals and the feedback treated accordingly in the amplifier.
- FIG. 1 is a partial circuit and partial block diagram of a Class D amplifier of the prior art.
- FIG. 2 is a partial circuit and partial block diagram of one embodiment of the amplifier of the present invention.
- FIG. 3 is a partial circuit and partial block diagram of a second embodiment of the amplifier of the present invention.
- FIG. 4 is a partial circuit and partial block diagram of third embodiment of the amplifier of the present invention.
- the pulse width modulated audio input signal from the modulator 22 is also applied to the amplifier 30, and the pulse width modulated output signal therefrom passed through one or more inverters as may be desired for amplification, buffering and proper phasing.
- the integrator 18 of Figure has been removed from the feedback loop in this embodiment of the present invention.
- the removal of the integrator from the feedback loop requires that the audio signal be pulse width modulated for comparison, but this may be accomplished outside of the feedback loop.
- Both of the input signals to the summing amplifier 30 may be applied to a single terminal of the amplifier, with a reference voltage being applied to the other input. This avoids common mode input signal swings and the associated error components.
- the input signals to each of the summing amplifier 30, the comparator 22 and the non-inverting amplifier 26 are all applied to a single terminal with a reference voltage applied to the other terminal to thereby improve common mode signal rejection. Because the audio input signal is compared at the input terminal of the comparator 22 with a resistive junction, the comparison is made at the same input signal level and the common mode input voltage range is not exercised.
- the differential-to-single-ended-converter 16 of the prior art may also be removed from the feedback loop by treating each half of the bridge driver in the output circuit 10 as a separate channel.
- all of the inverters are CMOS devices such as the Harris® CD 54/74 HCU04 inverter which typically has a gain of 16 or 24 dB. Because of the gain available with such inverters, the amplifier 30 may be eliminated.
- CMOS inverters may be used with the embodiments of the other figures, but generally are not required.
- CMOS inverters also permits the use of a digitally generated pulse width audio signal, suitably processed, as the input signal to the amplifier.
- a suitable electronic switch may be used to substitute a digital source 36 such as a compact disc or CD for the illustrated audio amplifier 26 and modulator 22.
- the use of an additional inverter may be used to provide the complementary signals A and B to the output circuit 10.
- the digital source may provide two separate signals directly to the inverters at the input of the output circuit 10.
- the pulse width modulated audio signal of the output terminal 32 is applied to two out of phase comparators 34 and 36 in a dual channel pulse width modulator 22 to thereby establish the complementary input signals A and B to the output circuit 10.
- the two channels may receive separate audio input signals.
- the operation of the switch SW2 may provide a completely independent pulse width modulated audio source 38 as the input source for the comparator or modulator 34 within the modulator 22.
- the invertor 40 may of course be omitted with the reversal of the connections at the comparator 34.
- the triangle waveform generator 24 needed for modulation may be common to both of the comparators 34 and 36 rather than associated with the audio sources as shown.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/512,763 US5672998A (en) | 1995-08-09 | 1995-08-09 | Class D amplifier and method |
KR1019960032750A KR970013651A (ko) | 1995-08-09 | 1996-08-06 | 개선된 d급 증폭기 및 방법 |
EP96401739A EP0758164A1 (fr) | 1995-08-09 | 1996-08-06 | Amplificateur amélioré classe D et méthode |
JP8208001A JPH09121128A (ja) | 1995-08-09 | 1996-08-07 | 改良されたクラスd増幅器および方法 |
CN96109421A CN1145551A (zh) | 1995-08-09 | 1996-08-09 | 改进的d类放大器及其实现方法 |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/512,763 US5672998A (en) | 1995-08-09 | 1995-08-09 | Class D amplifier and method |
Publications (1)
Publication Number | Publication Date |
---|---|
US5672998A true US5672998A (en) | 1997-09-30 |
Family
ID=24040454
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/512,763 Expired - Fee Related US5672998A (en) | 1995-08-09 | 1995-08-09 | Class D amplifier and method |
Country Status (5)
Country | Link |
---|---|
US (1) | US5672998A (fr) |
EP (1) | EP0758164A1 (fr) |
JP (1) | JPH09121128A (fr) |
KR (1) | KR970013651A (fr) |
CN (1) | CN1145551A (fr) |
Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5848147A (en) * | 1995-11-29 | 1998-12-08 | U.S. Philips Corporation | Terminal for wirebound telecommunication |
US6118336A (en) * | 1998-10-30 | 2000-09-12 | Intersil Corporation | Start-up circuit for self oscillating class D modulator |
US6127885A (en) * | 1998-08-31 | 2000-10-03 | Cello, Limited | Class D amplifiers including transition zone modulation |
US6211735B1 (en) * | 2000-01-21 | 2001-04-03 | Harris Corporation | RF power amplifier having improved power supply for RF drive circuits |
US6294957B1 (en) * | 2000-01-21 | 2001-09-25 | Harris Corporation | RF power amplifier having synchronous RF drive |
US6346852B1 (en) * | 1999-04-27 | 2002-02-12 | Stmicroeletronics S.R.L. | Class-D amplifier with enhanced bandwidth |
US6597241B1 (en) * | 1999-10-04 | 2003-07-22 | Alcatel | High performance audio transmission channel |
US20030184376A1 (en) * | 2002-04-02 | 2003-10-02 | Horst Knoedgen | Class D amplifier energy control |
US20040017252A1 (en) * | 2002-07-24 | 2004-01-29 | Katsumi Miyazaki | Current chopper-type D class power amplifier |
US6970503B1 (en) * | 2000-04-21 | 2005-11-29 | National Semiconductor Corporation | Apparatus and method for converting analog signal to pulse-width-modulated signal |
US20070109049A1 (en) * | 2005-11-03 | 2007-05-17 | Kuo-Hung Wu | Filterless class d power amplifier |
US20070140513A1 (en) * | 2005-12-15 | 2007-06-21 | Harman International Industries, Incorporated | Distortion compensation |
US20070146069A1 (en) * | 2005-12-27 | 2007-06-28 | Kuo-Hung Wu | Filterless class D power amplifier |
US20070273437A1 (en) * | 2006-05-15 | 2007-11-29 | Asahi Kasei Emd Corporation. | Driving device |
US20070290726A1 (en) * | 2006-05-15 | 2007-12-20 | Toshio Kaiho | Driving device and driving method |
US20090243745A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of shaping a power spectrum in pwm amplifiers |
US20090243744A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of changing a pwm power spectrum |
US20090243688A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of changing a pwm power spectrum |
US8130128B2 (en) | 2010-03-30 | 2012-03-06 | Silicon Laboratores Inc. | System and method for generating shaped noise |
CN101527546B (zh) * | 2008-03-07 | 2013-02-13 | 成都芯源系统有限公司 | 一种d类功率放大器 |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5767740A (en) * | 1996-09-27 | 1998-06-16 | Harris Corporation | Switching amplifier closed loop dual comparator modulation technique |
IL129270A0 (en) * | 1999-03-30 | 2000-02-17 | Dip Digital Power Ltd | Class "d" amplifier |
US6404251B1 (en) * | 2000-03-27 | 2002-06-11 | Linear Technology Corporation | Systems and methods for linearly varying a pulse-width modulation signal with a control signal |
JP3776392B2 (ja) * | 2002-10-03 | 2006-05-17 | 三菱電機株式会社 | D級増幅器 |
JP4078543B2 (ja) * | 2002-12-20 | 2008-04-23 | ソニー株式会社 | オーディオアンプ |
US8243960B2 (en) * | 2010-03-04 | 2012-08-14 | Bose Corporation | Planar audio amplifier output inductor with current sense |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4390849A (en) * | 1980-05-07 | 1983-06-28 | Itt Industries, Inc. | Audio power amplifier with class-D push-pull output stage |
US4458208A (en) * | 1981-04-10 | 1984-07-03 | Sony Corporation | Pulse width modulated signal amplifier |
US4968948A (en) * | 1988-12-28 | 1990-11-06 | Pioneer Electronic Corporation | Pulse width modulation amplifier circuit |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5818804B2 (ja) * | 1974-12-18 | 1983-04-14 | ソニー株式会社 | パルス幅変調増巾回路 |
EP0504460B1 (fr) * | 1991-03-21 | 1995-02-01 | Siemens Audiologische Technik GmbH | Prothèse auditive avec un étage amplificateur de sortie à commutation |
-
1995
- 1995-08-09 US US08/512,763 patent/US5672998A/en not_active Expired - Fee Related
-
1996
- 1996-08-06 EP EP96401739A patent/EP0758164A1/fr not_active Ceased
- 1996-08-06 KR KR1019960032750A patent/KR970013651A/ko not_active Application Discontinuation
- 1996-08-07 JP JP8208001A patent/JPH09121128A/ja active Pending
- 1996-08-09 CN CN96109421A patent/CN1145551A/zh active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4390849A (en) * | 1980-05-07 | 1983-06-28 | Itt Industries, Inc. | Audio power amplifier with class-D push-pull output stage |
US4458208A (en) * | 1981-04-10 | 1984-07-03 | Sony Corporation | Pulse width modulated signal amplifier |
US4968948A (en) * | 1988-12-28 | 1990-11-06 | Pioneer Electronic Corporation | Pulse width modulation amplifier circuit |
Cited By (41)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5848147A (en) * | 1995-11-29 | 1998-12-08 | U.S. Philips Corporation | Terminal for wirebound telecommunication |
US6127885A (en) * | 1998-08-31 | 2000-10-03 | Cello, Limited | Class D amplifiers including transition zone modulation |
US6118336A (en) * | 1998-10-30 | 2000-09-12 | Intersil Corporation | Start-up circuit for self oscillating class D modulator |
US6346852B1 (en) * | 1999-04-27 | 2002-02-12 | Stmicroeletronics S.R.L. | Class-D amplifier with enhanced bandwidth |
US6597241B1 (en) * | 1999-10-04 | 2003-07-22 | Alcatel | High performance audio transmission channel |
US6211735B1 (en) * | 2000-01-21 | 2001-04-03 | Harris Corporation | RF power amplifier having improved power supply for RF drive circuits |
US6294957B1 (en) * | 2000-01-21 | 2001-09-25 | Harris Corporation | RF power amplifier having synchronous RF drive |
US6970503B1 (en) * | 2000-04-21 | 2005-11-29 | National Semiconductor Corporation | Apparatus and method for converting analog signal to pulse-width-modulated signal |
US20030184376A1 (en) * | 2002-04-02 | 2003-10-02 | Horst Knoedgen | Class D amplifier energy control |
US6750705B2 (en) | 2002-04-02 | 2004-06-15 | Dialog Semiconductor Gmbh | Class D amplifier energy control |
US20040017252A1 (en) * | 2002-07-24 | 2004-01-29 | Katsumi Miyazaki | Current chopper-type D class power amplifier |
US20070109049A1 (en) * | 2005-11-03 | 2007-05-17 | Kuo-Hung Wu | Filterless class d power amplifier |
US7355473B2 (en) | 2005-11-03 | 2008-04-08 | Amazion Electronics, Inc. | Filterless class D power amplifier |
US20070140513A1 (en) * | 2005-12-15 | 2007-06-21 | Harman International Industries, Incorporated | Distortion compensation |
US8942391B2 (en) | 2005-12-15 | 2015-01-27 | Harman International Industries, Incorporated | Distortion compensation |
US8036402B2 (en) | 2005-12-15 | 2011-10-11 | Harman International Industries, Incorporated | Distortion compensation |
US7332962B2 (en) | 2005-12-27 | 2008-02-19 | Amazion Electronics, Inc. | Filterless class D power amplifier |
US20070146069A1 (en) * | 2005-12-27 | 2007-06-28 | Kuo-Hung Wu | Filterless class D power amplifier |
US20070273437A1 (en) * | 2006-05-15 | 2007-11-29 | Asahi Kasei Emd Corporation. | Driving device |
US20070290726A1 (en) * | 2006-05-15 | 2007-12-20 | Toshio Kaiho | Driving device and driving method |
US7463090B2 (en) * | 2006-05-15 | 2008-12-09 | Asahi Kasei Emd Corporation | Driving device |
US7656202B2 (en) | 2006-05-15 | 2010-02-02 | Asahi Kasei Emd Corporation | Driving device and driving method |
KR100977505B1 (ko) * | 2006-05-15 | 2010-08-23 | 아사히 가세이 일렉트로닉스 가부시끼가이샤 | 구동 장치 |
CN101527546B (zh) * | 2008-03-07 | 2013-02-13 | 成都芯源系统有限公司 | 一种d类功率放大器 |
US20090243744A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of changing a pwm power spectrum |
US7924200B2 (en) | 2008-04-01 | 2011-04-12 | Silicon Laboratories, Inc. | System and method of altering a PWM carrier power spectrum |
US7724105B2 (en) | 2008-04-01 | 2010-05-25 | Silicon Laboratories, Inc. | System and method of shaping a power spectrum in PWM amplifiers |
US20100171540A1 (en) * | 2008-04-01 | 2010-07-08 | Silicon Laboratories, Inc. | System and Method of Changing a PWM Power Spectrum |
US20100207699A1 (en) * | 2008-04-01 | 2010-08-19 | Silicon Laboratories, Inc. | System and Method of Shaping a Power Spectrum in PWM Amplifiers |
US7598895B1 (en) | 2008-04-01 | 2009-10-06 | Silicon Laboratories, Inc. | System and method of altering a PWM carrier power spectrum |
US7791521B2 (en) | 2008-04-01 | 2010-09-07 | Silicon Laboratories, Inc. | System and method of changing a PWM power spectrum |
US20100296671A1 (en) * | 2008-04-01 | 2010-11-25 | Silicon Laboratories, Inc. | System and Method of Changing a PWM Power Spectrum |
US20110019728A1 (en) * | 2008-04-01 | 2011-01-27 | Silicon Laboratories, Inc. | System and method of altering a pwm carrier power spectrum |
US7701307B2 (en) | 2008-04-01 | 2010-04-20 | Silicon Laboratories, Inc. | System and method of changing a PWM power spectrum |
US7965214B2 (en) | 2008-04-01 | 2011-06-21 | Silicon Laboratories Inc. | System and method of changing a PWM power spectrum |
US20090243903A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of altering a pwm carrier power spectrum |
US20090243745A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of shaping a power spectrum in pwm amplifiers |
US8154358B2 (en) | 2008-04-01 | 2012-04-10 | Silicon Laboratories, Inc. | System and method of changing a PWM power spectrum |
US8188804B2 (en) | 2008-04-01 | 2012-05-29 | Silicon Laboratories, Inc. | System and method of shaping a power spectrum in PWM amplifiers |
US20090243688A1 (en) * | 2008-04-01 | 2009-10-01 | Silicon Laboratories Inc. | System and method of changing a pwm power spectrum |
US8130128B2 (en) | 2010-03-30 | 2012-03-06 | Silicon Laboratores Inc. | System and method for generating shaped noise |
Also Published As
Publication number | Publication date |
---|---|
KR970013651A (ko) | 1997-03-29 |
CN1145551A (zh) | 1997-03-19 |
JPH09121128A (ja) | 1997-05-06 |
EP0758164A1 (fr) | 1997-02-12 |
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Owner name: HARRIS CORPORATION, FLORIDA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:WITTLINGER, HAROLD ALLEN;REEL/FRAME:007612/0276 Effective date: 19950809 |
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